| Background: Titanium and its alloys are widely used as human implant materials,such as orthopedic implants and oral implants,due to their low density,high mechanical properties and excellent chemical stability;however,the lack of specific biological properties in the complex environment of human body leads to its therapeutic effect to be improved,such as insufficient antibacterial properties leading to infection complications and insufficient biocompatibility leading to poor osseointegration.Surface modification to impart specific properties to the surface is considered as an effective solution while maintaining the properties of the material itself.Traditional surface modification methods often involve complicated physical and chemical reactions,resulting in complex operation,poor repeatability and difficult to meet the needs of clinical diversification,there is an urgent need to develop a simpler,flexible,and feasible modification strategy.At the beginning of the 21 st century,Lee et al.developed a versatile biological coating,polydopamine coating,based on mussel chemistry.The oxidation of catechol in the dopamine molecule to quinone groups can react with primary amine groups to form a polydopamine coating by self-polymerization under alkaline conditions.It can not only firmly adhere to most materials,but also serve as a platform for subsequent surface modification of functional molecules,which is a simple surface modification method for operation.However,subsequent studies found that the number and variety of active functional groups on the surface of polydopamine coatings are limited,which is not conducive to subsequent grafting of bioactive molecules,and dopamine may cause neurotoxicity and cytotoxicity.In this work,the phenolamine coating(polydopamine-like coating)with good biocompatibility and re-fixation of active molecules is prepared on the titanium surface through the interaction between the o-phenolic group of polyphenols and the amino group of hexanediamine,which can not only retain the advantages of polydopamine coating,but also meet the needs of multi-functional surface modification.Purposes: Based on the idea of biomimetic mussel protein,this study selected three different polyphenols as o-phenol donors and hexanediamine as amino donors.By adjusting the ratio of polyphenols and hexanediamine,different phenolamine crosslinked coatings were constructed on the surface of porous titanium by liquid phase deposition.The effect of coating preparation factors on the properties of the coating was investigated by material characterization and biocompatibility evaluation of the coating,and the number of amino groups on the surface for secondary reaction was measured.Taking the prevention of implant infection as an example,the ability of chlorhexidine grafted coating and the stability of the grafted coating were explored.This study provides a reference for the construction of phenolamine crosslinked coating and a simple and effective modification platform for the construction of oral implant antibacterial surface.Methods: The o-phenol group donors(group A)were three polyphenolic substances,tannic acid(TA),phlorotannin(PL)and epigallocatechin gallate(EGCG),amine donor(group B)was hexanediamine(HD).The titanium sheet with a diameter of 1 cm was polished smoothly,and then ultrasonically cleaned with acetone,anhydrous ethanol and deionized water for three times,15 min each time.After drying,it was immersed in 2.5mol / L Na OH solution and placed in a 60 °C drying oven for 24 h.After boiling water cleaning and drying,it was marked as p Ti.With Tris solution as the solvent,each polyphenol substance in group A was allocated to a concentration of 2 mg / m L,and each polyphenol was mixed with 0.2 mg / m L,2 mg / m L,and 10 mg / m L hexanediamine in equal volume,respectively,to a mixed solution with a concentration ratio of 1: 0.1,1: 1,and 1: 5.p Ti was immersed in the mixed solution and reacted at room temperature for 24 h.The ultrapure water of titanium plate was taken out and ultrasonically cleaned three times,and the samples deposited with phenolamine were obtained after drying.The material science characterization was performed by scanning electron microscopy,X-ray photoelectron analysis(XPS),static water contact angle and amino acid quantification,methyl thiazolyl tetrazolium(MTT)method and cytofluoric staining to evaluate the cytocompatibility of each group of samples,secondary grafting ability test to evaluate the ability of the coating to graft chlorhexidine,and immersion test to evaluate the stability of the coating after grafting.Results: Scanning electron microscopy showed that when the concentration ratio was 1:5,the surface of the three groups of phenolamine coatings had fewer spherical particles and showed a uniformly coated porous structure.XPS results showed that the Ti2 p peak disappeared and the C1 s peak increased in each phenolamine group.With the increase of concentration ratio(i.e.,the proportion of amino donor increased),the N1 s peak appeared and gradually increased,and the O1 s peak gradually weakened,indicating that the phenolamine coating had been successfully constructed.The change of hydrophilicity in the water contact angle results before and after coating preparation also indirectly proved the successful construction of phenolamine coating.Amino quantification showed that with the increase of concentration ratio,the amino groups on the surface of phenolamine group increased continuously,and the content of p Ti-EGCG / HD group was the highest when the concentration ratio was 1: 5.The results of biocompatibility showed that compared with p Ti,the number of cells adhered to the surface of the phenolamine group was more after 3 days of culture,and the cells stretched out pseudopodia,showing a healthy spindle shape.The cell activity on the surface of p Ti-EGCG / HD was the best.The SEM results of the secondary grafting ability test showed that the spherical particles on the coating surface were reduced.XPS analysis showed the appearance of characteristic Cl2 p peak and the enhancement of N1 s peak on the surface of p Ti-EGCG /HD / CHX group,indicating that chlorhexidine had been successfully grafted on the coating surface.The increase of water contact angle also proves the successful grafting of chlorhexidine from the side.The antibacterial experiment showed that the p Ti-EGCG/ HD / CHX group had good antibacterial performance when the concentration ratio was1: 5.The stability test also showed that the p Ti-EGCG / HD / CHX group at the concentration ratio of 1: 5 could still exert antibacterial effect after long time immersion.Conclusion: In this study,three phenolamine crosslinked coatings were successfully constructed on the surface of titanium through the combination of three polyphenols and hexanediamine.p Ti-EGCG / HD coatings show good biocompatibility with more reactive groups.Then,the ability of p Ti-EGCG / HD coatings to graft chlorhexidine and the stability of the grafted coating were studied.The results showed that p Ti-EGCG / HD coatings were successfully grafted with chlorhexidine,and the p Ti-EGCG / HD / CHX coating at the concentration ratio of 1: 5 had excellent and long-term stable antibacterial properties.This biological coating based on phenolic amine chemistry can provide an excellent platform for functional modification of dental implants. |
PDF Full Text Request